Input.xaml

<Window
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="MainWindow"
    SizeToContent="WidthAndHeight"
    FontFamily="Consolas"
    FontSize="14"
    FocusManager.FocusedElement="{Binding ElementName=Value}"
    Topmost="True">
    <Window.Resources>
        <Style TargetType="Control" x:Key="Margin">
            <Setter Property="Margin" Value="5" />
        </Style>
        <Style TargetType="Button" BasedOn="{StaticResource Margin}">
            <Setter Property="Background" Value="LightBlue" />
            <Setter Property="Height" Value="30" />
            <Setter Property="Width" Value="100" />
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="Button">
                        <Border
                            CornerRadius="5"
                            BorderThickness="1"
                            Background="{TemplateBinding Background}">
                            <ContentPresenter
                                Content="{TemplateBinding Content}"
                                HorizontalAlignment="Center"
                                VerticalAlignment="Center" />
                        </Border>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
            <Style.Triggers>
                <Trigger Property="IsMouseOver" Value="True">
                    <Setter Property="Background" Value="Cyan" />
                </Trigger>
            </Style.Triggers>
        </Style>
    </Window.Resources>
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="Auto" />
            <ColumnDefinition Width="Auto" />
            <ColumnDefinition Width="Auto" />
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="1*" />
            <RowDefinition Height="2*" />
        </Grid.RowDefinitions>
        <TextBlock Name="Prompt" Grid.ColumnSpan="3" Margin="5" />
        <TextBox
            Grid.Row="1"
            Name="Value"
            Style="{StaticResource Margin}"
            MaxLines="4"
            AcceptsReturn="True"
            SpellCheck.IsEnabled="True"
            Language="en-US"
            Width="600" />
        <Button
            Name="OK"
            Grid.Row="1"
            Grid.Column="1">
            <AccessText>
                _OK
            </AccessText>
        </Button>
        <Button
            Name="Cancel"
            Grid.Row="1"
            Grid.Column="2">
            <AccessText>
                _Cancel
            </AccessText>
        </Button>
    </Grid>
</Window>